We have outlined studies designed to investigate the role of oxygen radicals in the interaction between mononuclear effector cells and secific tumor cell targets. The systems we will study include immune T cell mediated cytolysis as well as antibody dependent cytotoxicity (ADCC) by K cells and monocyte (macrophages). We will determine whether or not there is any correlation between the sensitivity of a target cell and its sensitivity to oxidant injury. We will determine whether or not lymphocytes can be induced to generate oxygen radicals in response to specific target stimuli or whether this biochemical function is limited to phagocytic cells. We believe that the proposed experiments will settle several important questions including whether or not cytotoxic effector cells generate oxygen radicals, which species of oxygen radicals are critical for cytolysis or cytostasis and whether or not differences in susceptibility to cytolysis among various target cells are related to differences in the ability to withstand oxidant injury.